An adaptive control scheme for emergency braking of vehicles is designed based on a LuGre dynamic model for the tire/road friction. The wheel angular speed and longitudinal vehicle acceleration information are used to design a fast convergence observer to estimate the vehicle velocity, friction internal state and the friction parameters. A Lyapunov-based stabilizing state estimator and a braking controller are designed to achieve near maximum braking capability of the vehicle. Underestimation of the friction coefficient is guaranteed by a proper choice of adaptation gains and initial conditions of the friction parameters. The simulation results show that both the state estimation and the friction parameters converge to the true values and that vehicle stops rapidly.